Transmission systems, dry transmissions particularly, are known in the art each including a splined input shaft which engages a complimentarily splined flange of a damper of the transmission system for transmitting the torque between the input shaft and the damper flange.
Grease is often used to lubricate the engagement of the flange splines with the input shaft splines, so that some degree of relative axial movement along the splines is possible between the input shaft and the flange. During assembly of the transmission system, prior to the engagement of the input shaft and the flange, grease is added to the splines of one or both of these parts. As the shaft and flange are fully engaged, some grease is stripped off of the splines, and gathers at the end of the shaft near the base of the flange. This grease may travel radially down the flange, away from the axis of rotation of the shaft and flange, due to centrifugal forces which are created by the rotation of the flange and input shaft.
While traveling down the flange, the grease may interfere with other components of the transmission system, such as a hysteresis or friction package of the damper. If the grease lubricates the hysteresis package, the damper will no longer work properly, negatively affecting the NVH, or noise, vibration, harshness characteristics of the damper.
U.S. Pat. Nos. 4,667,968 (Nash et al.) and 6,692,007 (Oldenburg) each teach a lip seal between the flange and input shaft for retaining grease. However, the lip seals taught in these references require a retention feature for holding the seals, so that the seals can in turn retain the grease. In order to install the lip seals, additional parts are required, and therefore a substantial amount of additional time and cost are also necessary. Furthermore, the lip seals occupy a substantial amount of room and therefore reduce the space that the splines can occupy, which will detrimentally affect performance of the transmission system.
Therefore, what is needed is a cost effective grease trap that is simple to install into a transmission for retaining grease proximate to the input shaft and out of a hysteresis package of the transmission.